1. Field of the Invention
The present invention relates to a print control device, a data processing method, a computer program, and a computer readable storage medium for generating, in response to an issued print request, print data interpretable by a printer from image data produced by an application, transferring the print data to the printer, and providing a print cancel function.
2. Description of the Related Art
Means for canceling a print operation is available in known printers. If any error is found in the middle of the printing operation performed through a printer driver, the means is used to cancel the print operation.
A control method for the print cancel is typically subject to the limitation of the function of an operating system (OS) and a printing system. For example, under an environment where multi-task operations relating to printing are enabled, a task of controlling the generation of print data and the transmission of the print data and a task of accepting a print cancel from the user are separately managed. The task of accepting the print cancel, constantly monitoring the presence of the print cancel request, receives the print cancel request at any timing.
Under an environment that permits no multitasking (under a single task environment), a printer in a typical control method thereof checks, during an interval between the generation of the print data and the transmission of the print data, whether a print cancel request is issued by the user.
In the above control method, the length of a time lag between the print cancel request issued by the user and an actual suspension of the printing operation is determined by time intervals between the checks of the issues of the print cancel request.
The time intervals between the checks of the issues of the print cancel request, if too short, adversely affect the speed of the generation of the print data and the transfer of the print data, both of which are major purposes of the printer. Conversely, if the time intervals are too long, the response to the print cancel request is degraded.
For example, the print cancel is checked every half page in the printing of a document of one page. Even if a print cancel button is pressed to issue a print cancel request immediately subsequent to the start of the printing operation, the printer driver is unable to detect the occurrence of the print cancel request until at least half the page is completed. The response to the print cancel request is thus delayed by duration of time required to print half the page.
The user typically desires to suspend an erroneous printing when the user notices the erroneous printing. A quick response to the print cancel is desired in many cases. If the time lag occurs during which the user is not sure whether or not the printer is currently responding to the request, the user typically presses the print cancel button repeatedly, and may fret about waiting.
In a printing system that spools print data before transferring the print data, a response delay to a print cancel request causes sheets to be consumed in vain if the print cancel request is detected after the generation of print data of a next page and the transfer of the print data have started.
Depending on print conditions, the printer driver detects the print cancel request sometimes quickly but sometimes slowly.
For example, a unit of throughput is 36 lines, and the presence or absence of the print cancel request is checked each time the printer driver receives image data of 36 lines from an application, produces print data and transfers the print data to a printer. The response to the print cancel request is different between color printing and monochrome printing. In the color printing operation, the print cancel request is checked after the time elapse for 36 lines times the number of colors (4 for the CMYK system, for example). In contrast, the monochrome printing allows the print cancel request to be checked each time data of 36 lines times one (monochrome) is processed.
The time difference between the color printing and the monochrome printing directly determines the response to the print cancel issued by the user. As a result, if the print cancel request is always checked every 36 lines, variations occur in the response.
This inconvenience occurs not only because of the difference between the color printing and monochrome printing, but also because of a resolution difference between 600 dpi and 300 dpi, or because of a sheet size difference between A4 and A3, even if the throughput remains unchanged from 36 lines. These differences also affect the response as much as the difference between the color printing and the monochrome printing does.
The uniform control of the monitoring time for detecting the print cancel request degrades the response feature depending on the print environment.